1) Field of the Invention
The present invention relates to a technology for correcting load and an angle of a suspension that supports a magnetic head slider of a hard disk drive.
2) Description of the Related Art
Recording densities of the hard disk drives have improved remarkably. As a result, the suspensions that supports the magnetic head in the hard disk drives needs to be manufactured with more precision than ever before.
The magnetic head is pressed against the magnetic disk while the magnetic disk is rotating. As a result, the magnetic head flies aerodynamically at a predetermined distance from the disk. The load, the fine roll angle, and the pitch angle of the suspension greatly affect the flying of the magnetic head. The load, the roll angle, and the pitch angle of each suspension are corrected during the manufacturing process.
A conventional approach to correct the load, the roll angle, and the pitch angle of the suspension is to correct them mechanically. Precisely, an outrigger of a flexure that holds the magnetic head is held mechanically, for example, by tool, and the outrigger is bent or twist in an appropriate direction. However, this approach requires a tool having an appropriate shape to hold the outrigger and a mechanism to move the tool. Thus, this approach is costly and troublesome.
Another conventional approach to correct the load, the roll angle, and the pitch angle of the suspension is to thermally deform the suspension by irradiating a laser beam to the suspension. This technique is disclosed, for example, in Japanese Patent Application Laid-open Publication No. 2000-339894 and Japanese Patent Application Laid-open Publication No. H7-77063.
According to the technique disclosed in Japanese Patent Application Laid-open Publication No. 2000-339894, the outrigger is scanned with a laser beam in a direction that is perpendicularly or oblique (i.e., a flexure width direction) to the arm longitudinal direction. The outrigger bends due to the thermal energy of the laser beam. In this manner, the roll angle and the pitch angle of the suspension can be corrected. Particularly, the laser beam is irradiated on the outrigger from a direction approximately perpendicular to a direction of curvature of the outrigger, moreover, the laser beam is made to enter from one end of the outrigger, scan the outrigger, and go out from the other end of the outrigger.
According to the technique disclosed in Japanese Patent Application Laid-open Publication No. H7-77063, a laser beam is irradiated to a width direction of a spring arm, thereby to correct the load and obtain a prescribed contact pressure. Even in this technique, the laser beam is made to enter from one end of the spring arm, scan the spring arm, go out from the other end of the spring arm.
Thus, in the conventional approaches, the laser beam is irradiated from a direction that is approximately perpendicularly or oblique to the direction in which the suspension is curved. As a result, it is difficult to control bending of the suspension with precision. In other words, when the suspension is looked at from a lateral direction, the outrigger is bent with the laser beam-scanned portion as a fulcrum. As a result, an error in the position of the scanning is amplified largely at the end portion of the suspension. Despite the necessity for forming the suspension in extremely high precision, it is difficult in the conventional approaches to carrying out a fine correction of the load, the roll angle, and the pitch angle of the suspension, or the conventional techniques require correction and inspection to be repeated many times. This leads to low productivity.